Titanium-based alloys and articles formed from such alloys

ABSTRACT

Article(s) are disclosed that are formed, at least in part, by a titanium-based alloy having about 35 to about 55 wt. % or greater titanium, the article(s) have a hardness of about 1350 HV or greater, and a coloration characterized by an L value of about 56.00 to about 60.00, an a value of about 1.0 to about 1.5, and a b value of about 3.65 to about 3.75, wherein the L, a, and b values are color values according to the CIE L*a*b* color scale.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. ProvisionalApplication Ser. No. 62/003,514 filed 27 May 2014, which is incorporatedherein by reference in its entirety

BACKGROUND

The present application generally relates to compositions of matter andarticles of manufacture, such as jewelry items.

In this specification where a document, act or item of knowledge isreferred to or discussed, this reference or discussion is not anadmission that the document, act or item of knowledge or any combinationthereof was at the priority date, publicly available, known to thepublic, part of common general knowledge, or otherwise constitutes priorart under the applicable statutory provisions; or is known to berelevant to an attempt to solve any problem with which thisspecification is concerned.

Jewelry such as finger rings, pendants, bracelets, and necklaces havetraditionally been made of soft metals such as gold, silver and platinumbecause those metals are malleable, and easily formed by casting,forging and molding. Recently, jewelry items have been formed fromharder materials such as alloys or composites such as “cermets.” Analloy is a mixture or metallic solid solution composed of two or moreelements. A cermet is a composite material composed of a ceramic andmetallic material. Typically, a metal is used as a binder for an oxide,boride, nitride, or carbide.

Some specific attempts to form jewelry from these types of materialsinclude alloys or composites having titanium, zirconium (U.S. Pat. No.3,669,695), titanium-niobium-zirconium (U.S. Pat. No. 6,759,134) andtungsten carbide (U.S. Pat. Nos. 6,553,667; 6,990,736; 6,993,842;7,032,314; 7,076,972). Such jewelry is much more resistant to scratchingand other damage than traditional jewelry made of softer metals.Additionally, certain alloys containing these metals, prepared undercertain conditions, have an attractive dark grey or black color. See,e.g., U.S. Pat. No. 6,759,134, describing articles made from an alloy of51-70 weight-percent (wt %) titanium, 3-17% niobium, and the balancezirconium, tantalum, molybdenum, hafnium zirconium, chromium, ormixtures thereof, having a black surface layer of a niobium oxide.

Additional alloy and composite formulations providing desirable jewelrycharacteristics would be advantageous. The articles provided herewithaddress that need. In particular, conventional jewelry materials canpossess one or more of the following deficiencies and/or disadvantages:

traditional formulations can be too heavy;

traditional formulations may not possess an optimal aesthetic colorationand/or shine or luster; and

-   -   traditional formulations may lack sufficient hardness.

While certain aspects of conventional technologies have been discussedto facilitate disclosure of the invention, Applicants in no way disclaimthese technical aspects, and it is contemplated that the claimedinvention may encompass or include one or more of the conventionaltechnical aspects discussed herein.

SUMMARY

It has been discovered that articles made from certain titanium-basedalloys, such as, for example, alloys having about 35% to about 55% Ti,among other constituents, which will be described in further detailherein, advantageously, according to certain embodiments, possess aunique combination of desirable features. For example, alloys formedaccording to the principles of the present invention possess desirablecoloration, hardness and density properties which makes themparticularly attractive for use in forming certain articles, such asarticles of jewelry.

Thus, according to one aspect of the present invention, there isprovided an article comprising a titanium-based alloy having about 35wt. % to about 55 wt. % titanium, the article having a hardness of about1300 HV or greater, and a coloration characterized by an “L” value ofabout 56 to about 60, an “a” value of about 1.0 to about 1.5, and a “b”value of about 3.7 to about 3.8, wherein the L, a, and b values arecolor values according to the CIE L*a*b* color scale.

An article formed according to the principles of the present inventionmay further possess a density of about 6.0 to about 6.35 g/cm3.

The remainder of the alloy composition may have one or more of: Si, Ta,Al, Mn, Nb, Zr and O.

The article of can be in the form of an item of jewelry.

The article may be in the form of a ring, a pendant, a dog tag, ahairclip, a chain, a watchcase, a pin, a bracelet, a necklace, anearring or a charm.

The article may be in the form of a finger ring.

The article may include at least one of a precious metal, a stone, agemstone, a crystal, or another material suitable for use in jewelryaffixed to the article.

The article may be in the form of a finger ring, and my have at leastone depression that extends into, and at least substantially around thecircumference of, an outer surface of the finger ring, wherein thedepression is substantially filled with a material, such as metal, or aprecious metal.

The present invention may address one or more of the problems anddeficiencies of the prior art discussed above. However, it iscontemplated that the invention may prove useful in addressing otherproblems and deficiencies, or provide benefits and advantages, in anumber of technical areas. Therefore the claimed invention should notnecessarily be construed as being limited to addressing any of theparticular problems or deficiencies discussed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a plain band-like finger ring inaccordance with an illustrative embodiment.

FIGS. 2A-2B are perspective views of finger rings that were machined inaccordance with an alternate illustrative embodiments.

FIG. 3 is a view of a finger ring that has been decoratively machined inaccordance with another alternate illustrative embodiment.

FIG. 4 is a view of a finger ring with a diamond inset.

DETAILED DESCRIPTION

As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. Additionally, the use of “or” is intended to include“and/or”, unless the context clearly indicates otherwise.

As used herein, “about” is a term of approximation and is intended toinclude minor variations in the literally stated amounts, as would beunderstood by those skilled in the art. Such variations include, forexample, standard deviations associated with techniques commonly used tomeasure the amounts of the constituent elements or components of analloy or composite material.

All of the numerical values contained in this disclosure are to beconstrued as being characterized by the above-described modifier“about,” are also intended to include the exact numerical valuesdisclosed herein. Moreover, all ranges include the upper and lowerlimits.

All percentages disclosed herein refer to percent by weight, relative tothe overall weight of the composition, unless otherwise describedherein. The weight percentages disclosed herein were measured by anInductively Coupled Mass Spectrometry (“ICP-MS”). ICP-MS is a type ofmass spectrometry capable of accurately measuring metals and non-metalsat very low concentrations. The sample is ionized by inductively coupledplasma and then the ions are separated and quantified by a massspectrometer. This technique is familiar to those skilled in the art.

The “HV” hardness number values described herein refer to the hardnessvalue measured according to the Vickers hardness test, performedaccording to the ASTM:E384-11^(ε1) standard (last revised March 2012).

As used herein, “L,” “a,” and “b,” refer to the color values measuredaccording to the CIE 1976 (L*, a*, b*) color space (or CIELAB) scale.These values disclosed herein were measured by a Konica MinoltaSpectrophotometer model CM-600.

All of the stated compositions and methods disclosed herein are to beconstrued as “comprising,” “consisting essentially of,” and “consistingof” the stated constituents and method steps.

Articles formed according to the principles of the present invention areformed, at least in part, from a particular alloy composition. Accordingto certain embodiments, the alloy composition is titanium-based.According to further embodiments, the alloy composition furtherincludes, in addition to titanium, one or more of tungsten, nickel,chromium, carbon, molybdenum and/or copper.

According to further alternative embodiments, the alloy composition isselected from a combination of one or more, or all, elements listed inthe table below, in any of the amounts described in the Table.

TABLE 1 Relative amounts in wt. %, modified in all cases Consituent bythe term “about” Ti 5-55, 35-55, 45, or 45.5 W no more than 60, 10-60,or 20 C 1-10, 8-20, 5-15, 10 or greater, or 12.7 or greater Cr .001-10,0-5, 2 or less, 1 or less, or 1.02 Mo .001-10, 1-10, 3-10, or 6.5 orgreater Cu .001-3.0, 0.5-2.0, 0.5-1.75, or trace Ni 5-25, 5-20, or 11

With respect to Ti, the alloy composition may include about 35-55 wt. %of Ti. Amounts of Ti below this threshold are not preferred becausedepending on which materials are used to replace Ti, the weight of thecomposition could increase, the hardness of the composition coulddecrease, the coloration may be modified in an unfavorable manner, andless than optimal or unfavored optical properties such as reflectivity,and other undesired changes to the composition may result. Compositionsthat include Ti in amounts beyond the upper limit of this range are notpreferred because, depending on which materials replace Ti in thecomposition, the alloy could exhibit increased brittleness, undesirablemodification coloration, reduced machine ability, and unfavorablechanges in optical properties such as reflectivity, and/or otherundesired changes to the properties of composition.

With respect to W, the alloy composition may include no more than about60 wt. % W. According to further embodiments, the alloy contains no morethan about 20% wt. % W. According to further optional embodiments, thealloy composition includes at least about 10 wt. % W.

With respect to Ni, the alloy composition may include about 5 to about20 wt. % Ni. Compositions that include Ni in amounts below the minimumvalue of this range are not preferred because such compositions tend toexhibit increased hardness of the solid solution elements, and resultingincreases in brittleness. Compositions that include Ni in amounts abovethe maximum value of this range are not preferred because suchcompositions exhibit a decrease in hardness of the alloy which in turnwill decrease the hardness, where resistance, corrosion resistance, aswell as increase the risk of allergic reaction based on the EN1811/2011standard.

With respect to Cr, the alloy composition may include no more than about2 wt. % Cr. Amounts of Cr above this level are not preferred becausesuch compositions exhibit undesired changes in coloration, opticalproperties such as reflectivity, hardness, and ductility. According tofurther optional embodiments, the alloy composition includes about 0 toabout 5 wt. % Cr. Compositions that include Cr in amounts below thelower limit of this range are not preferred because such compositionsexhibit undesirable changes in coloration, optical properties such asreflectivity, hardness, and ductility.

Carbon exists in the composition in the form of a carbide with W and Tiin solid solution. With respect to C, the alloy composition may includeabout 10 wt. % or greater C. Amounts of C below this threshold are notpreferred because enough carbon should be present such that it can formcarbides with W and Ti in solid solution. According to further optionalembodiments, the alloy composition includes about 8 to about 20 wt. % C.Compositions that include C in amounts beyond the upper limit of thisrange are not preferred because compositions having carbon in suchamounts form excess carbides which in turn result in increasedbrittleness of sintered parts and cause unwanted binding orcarbonization with other free elements.

With respect to Mo, the alloy composition may include about 6.5 wt. % orgreater Mo. Amounts of Mo below this threshold are not preferred becauseunfavorable changes in ductility, coloration and reflectivity of thecomposition may result. According to further optional embodiments, thealloy composition includes about 3 to about 10 wt. % Mo. Compositionsthat include Mo in amounts beyond the upper limit of this range are notpreferred because substantial changes in ductility, coloration,composition and reflectivity may occur. As an example, a substantialincrease in ductility will make the finished parts, such as parts in theform of a finger ring, difficult to remove by breaking in a vice in theevent of an emergency, thus necessitating the use of more dangerous andless favorable means (e.g., wet cutting using a circular diamondgrinding wheel) in order to break the ring and remove it from the fingerif necessary.

With respect to Cu, the alloy composition may include about 0.5 to about2.0 wt. % Cu. Compositions that include Cu in amounts below the minimumvalue of this range are not preferred because property such asductility, fusion temperature and coloration may be impacted in anadverse manner. Compositions that include Cu in amounts above themaximum value of this range are not preferred because such compositionsincrease the potential peroxidation breakdown of the metal matrix,thereby decreasing the where resistance and lifespan of finishedarticles such as jewelry pieces.

Alloy compositions formed according to the principles of the presentinvention may include, in addition to the above-described elements, oneor more of the following constituent elements, in relatively minoramounts: Si, Ta, Al, Mn, Nb, Zr, and/or O.

Alloy compositions formed according to further embodiments of thepresent invention preferably do not include cobalt (Co) or iron (Fe).More specifically, neither Co nor Fe are intentionally added asconstituent components of the alloy composition. However, trace amountsof these elements may be found in compositions formed according to thepresent invention. For example, modern steelmaking techniques utilizingcommercially available starting materials may introduce trace amounts ofthese elements into the composition unintentionally.

According to one specific exemplary, and non-limiting embodiment, anarticle formed from an alloy according to the principles of the presentinvention possesses the following:

TABLE 2 Value/Weight Property/Constituent Percent HV (Hardness) 1350Titanium (Ti) 45.5% Tungsten (W) 20.1% Nickel (Ni) 10.8% Chromium (Cr) 1.0% Cobalt (Co)  0.0% Carbon (C) 12.8% Iron (Fe)  0.0% Molybdenum (Mo) 6.6% Copper (Cu)  1.5% Silicon (Si) 0.09% Tantalum (Ta) 0.04% Aluminum(Al) 0.21% Manganese (Mn) 0.01% Niobium (Nb) 0.01% Zirconium (Zr) 0.01%Oxygen (O) 0.20%

In some embodiments, the entire article is made from the alloy. In otherembodiments, only a portion of the article is made from the alloy. Forexample, the decorative portion of a pin can be made from the alloy andthe rest of the pin can be made from standard materials. Where thearticle is a finger ring, the alloy can comprise the majority of thering, except for an inlaid gemstone, or an inlay in an annular grooveformed in the alloy, e.g., as illustrated in relation to rings made fromtungsten carbide in U.S. Pat. No. 7,076,972. Those rings have at leastone depression that extends into, and at least substantially around thecircumference of, an outer surface of the finger ring. In someembodiments, the depression in those rings is substantially filled witha precious metal.

In additional embodiments, the alloy can comprise a minority of thearticle, for example as a portion of a sculpture primarily made of othermaterials, or as a contrasting band in a ring made primarily fromanother metal such as gold or silver.

In some embodiments, the article is a decorative or artistic item, forexample, a sculpture, a portion of a picture frame, a paperweight, aportion of a piece of furniture (e.g., an inlay), or jewelry.Nonlimiting examples of jewelry that can be made from the Ti-based alloyare rings (e.g., finger rings, toe rings, nose rings), pendants, tags,dog tags, hairclips, chains, watchcases, pins, bracelets, anklets,necklaces, earrings and charms.

The item of jewelry comprising the alloy can further comprise any othermaterial used in jewelry affixed or integrated into the item. Examplesinclude a precious metal (e.g., gold, silver, platinum) either as partof the alloy or affixed to the item, a stone, a gemstone, a crystal, orany other material suitable for use in jewelry affixed to the item.

In particular embodiments, the item of jewelry is a finger ring. Thering can be made entirely of the alloy, or the ring can further compriseother materials, for example an inlaid gemstone, or an inlay in anannular groove formed in the alloy. Illustrative examples of fingerrings are provided in FIGS. 1-4. FIG. 1 shows a plain band-like ringmade from the Ti-based alloy described herein. FIGS. 2A-2B show otherexamples of finger rings made from the Ti-based alloy. These rings weremachined after preparation. FIG. 3 shows an additional example of afinger ring made from the Ti-based alloy that has a decorative patternmachined therein. FIG. 4 illustrates a ring having a diamond set thereinas a further example of a finger ring made from the Ti-based alloy.

The articles provided here can be made by any method known. In someembodiments, an ingot, bar, sheet or other form of the alloy isprovided, followed by cutting, shaping and polishing the ingot or bar toform a piece having a desired shape, then optionally polishing the piecewith a finish polish.

A “blank” of the article can then be cut from the bar or sheet, forexample using wire electric discharge machining (EDM). Any internalareas that need to be hollowed out of the blank (e.g., the centerportion of a ring) can be removed, e.g., using a sink EDM. A CNC lathecan then be used to prepare the outer shape of the article, followed bypolishing. At this point, any inlays, setting or engraving can beperformed. Where the article is a ring or similar article that requiresinternal sizing, a CNC lathe, followed by an inner polish can be used atthis point.

After the above shaping of the article, the article can be subjected toone or more heat treatment(s), followed by final polishing followed andany additional engraving desired, for example using a CNC lathe or CNCengraving.

Alternatively, articles having any of the compositions described hereincan be formed by a powder metallurgy process, wherein theabove-described constituent components are blended in powder form, thenpressed or injected to form a blank. The constituents described hereinmay be provided in their elemental powdered form. Alternatively, thepowders may themselves be combinations of different metals orconstituent components. The blank may approximate the final shape orform of the article. This is often referred to as “near-net-shape.” Theblank can them be consolidated by sintering. The result of the sinteringis a dense object possessing the desired coloration, etc. Onenon-limiting example of a possible powder metallurgy based formationtechnique is Hot Isostatic Pressing (HIP).

An article, such as any of the articles of jewelry described herein,formed at least in part from cermet can be produced by any suitabletechnique that results in a dense object having the desired physicalproperties as well as the desired coloration. For example, suitablemethods may comprise combining the constituent elements in powder form,pressing or injecting the powders to form a blank or near net-shapeobject, and sintering to consolidate the blank or object and provide agrey/dark grey/black appearance. Examples of specific techniques forpressing, injecting, molding and sintering to form a final article, suchas an article of jewelry, have been previously described above inconnection with powder metallurgical techniques. These techniques canalso be used to form articles, such as articles of jewelry, and areincorporated herein by reference. For example, the methods or techniquesdescribed in the United States Patent Application Publication No. US2012-0304694 may be used, the content of which is incorporated herein byreference in its entirety.

Articles formed according to the principles of the present invention,including the articles of jewelry described herein, may have one or moreadvantageous properties and/or characteristics.

According to certain embodiments, articles formed according to theprinciples of the present invention possess a Vickers hardness number(HV) of about 900 HV, 1200 HV, 1300 HV or greater. according to onespecific, illustrative, and non-limiting example, an article formedaccording to the principles of the present invention possesses an HVvalue of about 1350 HV, or greater than 1350 HV.

According to additional embodiments of the present invention, an articleformed according to the principles of the present invention possesses acoloration characterized by a range of L, a, and b values. Morespecifically, articles formed according to the principles of the presentinvention possess a “L” value of about 57 to about 59. According tofurther embodiments, the articles further possess an “a” value of about1.0 to about 1.5. According to additional embodiments, the articlesfurther possess a “b” value of about 3.7 to about 3.8. According to oneillustrative, non-limiting example, an article formed according to theprinciples of the present invention possesses a coloration characterizedas: L=about 58.01, a=about 1.08, and b=about 3.74.

According to still other embodiments of the present invention, articlescan be formed which possess a favorable density property. Morespecifically, articles formed according to the principles of the presentinvention may possess density values of about 6.0 to about 6.35 g/cm³.According to one specific, illustrative, and non-limiting example, anarticle formed according to the principle the present inventionpossesses a density value of about 6.2 g/cm³.

When compositions formed according to the principles of the presentinvention are utilized to produce articles of jewelry to be worn on thebody, another important property is the ability of such articles formedthereby to be removed from the body in the event of an emergency. Thus,the compositions formulated according to the principles of the presentinvention have been designed to serve the need of a lightweight scratchresistant product, yet still have the ability to be removed byconventional techniques involving applying pressure to the articlejewelry in a vice-like handheld or stationary tool. Alternatively, awelding laser can be used to weaken the structure of the articlejewelry. When such a welding laser is used, cool and should be used inconjunction with a moderately applied laser contact. Once the surface ofthe ring has been compromised, it can be more easily fractured andremoved. Appropriate settings for such an industrial welding laser mayinclude: voltage (220 V-240 V), cycle (5-5.5 Hz), and application time(3.25-3.5 milliseconds).

A similar consideration of the composition when utilized to producefinished articles in the form of jewelry is the ease in which thematerial can be engraved or removed for decorative purposes.Accordingly, the compositions formulated according to the principles ofthe present invention have been designed so as to facilitate laserengraving of decorative patterns thereon, and the like. Appropriatelaser settings can be determined by those skilled in the art. Accordingto certain illustrative and nonlimiting examples, appropriate lasersettings may include: power (19.8 W), cycle speed (7000 Hz), rotationspeed (100 mm/s). A desirable depth of cut can be achieved to render anaesthetically pleasing design.

Other embodiments within the scope of the claims herein will be apparentto one skilled in the art from consideration of the specification orpractice of the invention as disclosed herein. It is intended that thespecification be considered exemplary only, with the scope and spirit ofthe invention being indicated by the claims.

In view of the above, it will be seen that the several advantages of theinvention are achieved and other advantages attained.

As various changes could be made in the above methods and compositionswithout departing from the scope of the invention, it is intended thatall matter contained in the above description shall be interpreted asillustrative and not in a limiting sense.

All references cited in this specification are hereby incorporated byreference. The discussion of the references herein is intended merely tosummarize the assertions made by the authors and no admission is madethat any reference constitutes prior art. Applicants reserve the rightto challenge the accuracy and pertinence of the cited references.

Any numbers expressing quantities of ingredients, constituents, reactionconditions, and so forth used in the specification are to be understoodas being modified in all instances by the term “about.” Notwithstandingthat the numerical ranges and parameters setting forth, the broad scopeof the subject matter presented herein are approximations, the numericalvalues set forth are indicated as precisely as possible. Any numericalvalue, however, may inherently contain certain errors or inaccuracies asevident from the standard deviation found in their respectivemeasurement techniques. None of the features recited herein should beinterpreted as invoking 35 U.S.C. §112, 6, unless the term “means” isexplicitly used.

1. An article comprising a titanium-based alloy having about 35 to about55 wt. % titanium, the article having a hardness of about 1350 HV orgreater, and a coloration characterized by an L value of about 56.00 toabout 60.00, an a value of about 1.0 to about 1.5, and a b value ofabout 3.65 to about 3.75, wherein the L, a, and b values are colorvalues according to the CIE L*a*b* color scale.
 2. The article of claim1, wherein the article has a density of about 6.0 to about 6.35 g/cm³.3. The article of claim 1, wherein the alloy has about 45 wt. % Ti. 4.The article of claim 1, wherein the alloy has no more than about 60 wt.% W.
 5. The article of claim 1, wherein the alloy has about 10 to about60 wt. % W.
 6. The article of claim 1, wherein the alloy has about 5 toabout 15 wt. % C.
 7. The article of claim 1, wherein the alloy has about12.7 wt. % C.
 8. The article of claim 1, wherein the alloy comprises nomore than about 10 wt. % Cr.
 9. The article of claim 1, wherein thealloy comprises about 0.001 to about 10 wt. % Cr.
 10. The article ofclaim 1, wherein the alloy comprises about 0.001 to about 10 wt. % Mo.11. The article of claim 1, wherein the alloy comprises about 6.5 wt. %or greater Mo.
 12. The article of claim 1, wherein the alloy comprisesabout 0.5 to about 1.75 wt. % Cu.
 13. The article of claim 1, whereinthe alloy comprises no more than trace amounts of Co and Fe.
 14. Thearticle of claim 1, wherein the alloy comprises: Ti: about 35 to about55 wt. %; W: about 10 to about 60 wt. %; Ni: about 5 to about 20 wt. %;Cr: about 0.001 to about 10 wt. %; C: about 5 to about 15 wt. %; Mo:about 0.001 to about 10 wt. %; and Cu: about 0.5 to about 1.75 wt. %.15. The article of claim 1, wherein the remainder of the alloycomposition comprises one or more of: Si, Ta, Al, Mn, Nb, Zr and O. 16.The article of claim 1, wherein the article is an item of jewelry. 17.The article of claim 16, wherein the item of jewelry is a ring, apendant, a dog tag, a hairclip, a chain, a watchcase, a pin, a bracelet,a necklace, an earring or a charm.
 18. The article of claim 16, whereinthe item of jewelry is a finger ring.
 19. The article of claim 16,further comprising at least one of a precious metal, a stone, agemstone, a crystal, or another material suitable for use in jewelryaffixed to the article.
 20. The article of claim 18, wherein the fingerring has at least one depression that extends into, and at leastsubstantially around the circumference of, an outer surface of thefinger ring, wherein the depression is substantially filled with amaterial.
 21. The article of claim 20, wherein the material is a metal.22. The article of claim 21, wherein the metal is a precious metal.